This section provides background information related to the disclosure, which is not necessarily prior art.
Carrier aggregation before LTE (Long Term Evolution) Rel-11 is carrier aggregation of a single base station node. An aggregated carrier of a terminal is constituted of one primary component carrier and at least one secondary component carrier. In a FDD (Frequency Division Duplex) mode, association between a downlink primary component carrier and an uplink primary component carrier is determined via a SIB2 (System Information Block 2) message. A PUCCH (Physical Uplink Control Channel) signal is transmitted on the uplink primary component carrier. Normally, only one uplink component carrier performs uplink data transmission. Change of the primary component carrier implies occurrence of a handoff behavior.
In a case where the carrier aggregation is performed between base stations, if a macro base station and a low power node are not in common baseband, then uplink carrier aggregation will occur, and the original primary component carrier setting and association rules are still valid. Since component carriers of the macro base station are mainly used for data transmission related to mobility control, the primary component carriers may include a downlink component carrier of the macro base station. If the uplink primary component carrier is still associated in accordance with the SIB2, then it cannot assist the macro base station in performing PUCCH shunting to alleviate the burden for an uplink control channel of a macro cell in a case where the base station and the low power node perform common baseband transmission. In addition, when the macro base station and the low power node perform CoMP (Coordinated Multi-Point) transmission, and particularly for a case where the macro base station serves as an uplink receiving node, it is unable to perform accurate power control. Further, a solution that takes the macro base station as a receiving node to perform uplink power control is not beneficial to reduce energy consumption of UE (User Equipment).